Saliva formation is essential for the maintenance of oral health. Control of salivary formation is mediated by the autonomic nervous system, which influences the ion, water and protein transport properties of salivary cells. In order to better understand the mechanisms involved in the regulation of salivary gland secretion, we have sought to study clonal lines of salivary cells which possess neurotransmitter signal transduction mechanisms coupled to functional cellular responses. The use of established cell lines offers several advantages over acute in vitro preparations: (1) long term studies can be carried out, (2) studies can be carried out on specific types of cloned cell lines which possess the same genetic background, and (3) somatic cell genetic and molecular biological techniques can be utilized to investigate various regulatory mechanisms. During this reporting period we have characterized several neurotransmitter responses in established human salivary epithelial cell lines in culture, and we have cloned several mutant cell lines which might be defective in processes subject to neurotransmitter regulation.